1. Field of the Invention
The present invention relates to a communication terminal which is connected to an IP (Internet Protocol) network and thus performs telephone call by a predetermined IP telephone method, a control method for the communication terminal, and a control program for the communication terminal.
2. Related Background Art
In recent years, the Internet becomes worldwide rapidly. In such a situation, because the Internet has an advantage of remarkably decreasing communication charges, an Internet telephone (hereinafter called an IP telephone) which uses the Internet gets a lot of attention. Here, in the IP telephone, a particularly dominant standard at present is a VoIP (Voice over Internet Protocol) based on ITU-T (International Telecommunication Union-Telecommunication Standardization Sector) Recommendation H.323 or the like, and various types of devices corresponding to the IP telephone based on such a standard are proposed.
Conventionally, a device structure for browsing various contents (a Web page, an FTP/GOPHER (File Transfer Protocol/Gopher) directory, a NetNews, etc.) on the Internet by using a personal computer is independent of a device structure for performing telephone call by using the IP telephone. However, in recent years, a device which is made by uniting these two kinds of devices is being achieved. Here, it should be noted, in the conventional device structure, the above various contents on the Internet are browsed by means of Web browser software in many cases in accordance with corresponding protocols such as an HTTP (HyperText Transport Protocol), an FTP (File Transfer Protocol), a Gopher protocol, an NNTP (Network News Transfer Protocol), and the like. Incidentally, the conventional device structure has advantages due to such unification. That is, for example, it is possible to browse net contents as performing telephone call, and it is also possible to make a call by simply designating telephone number information included in a net content. Here, it should be noted that such a function to browse the net content as performing the telephone call is remarkably different from a conventional telephone function, whereby it is expected that various services concerning this function develop in the future.
However, in the present circumstances, it is necessary for a user who uses the above united device to actively browse the net content. That is, because a user operation to use the telephone is different from a user operation to perform the net content browsing, there is a problem that the content browsing operation which is complicated as compared with the telephone call operation is appropriately necessary for the user in addition to the telephone call operation. Thus, in consideration of such a problem, it is demanded to improve usability of the above united device.
Incidentally, as to display control of a browser for browsing the net contents (mainly Web pages, etc.) among plural terminals, following techniques are known.
For example, Japanese Patent Application Laid-Open No. 11-306116 discloses that, in order to display the same Web page on two client terminals, a URL (Uniform Resource Locater) appropriately designated by a user of one client terminal is transmitted to the other client terminal, and the content corresponding to the URL in question is displayed by the browser. However, in that case, the user of one client terminal has to perform the operation for designating the URL which is intended to be displayed on the other client terminal. For this reason, as compared with a conventional method that a user notifies a communication party of a URL through voices and mails, a user load cannot be reduced too much in Japanese Patent Application Laid-Open No. 11-306116.
Likewise, Japanese Patent Application Laid-Open No. 2000-341341 discloses that, in order to display the same Web page on plural client terminals, the URL of the content of the Web page in question or the content itself is transmitted and received through a transmission network which is different from that used for the communication between these client terminals. However, such a structure is premised on a television telephone, whereby the structure itself is complicated and expensive because it uses the transmission network different from that used in television telephone communication. That is, Japanese Patent Application Laid-Open No. 2000-341341 cannot be directly used in voice communication such as IP telephone communication.
Moreover, Japanese Patent Application Laid-Open No. 2002-149640 discloses that the same Web page is displayed on two terminals, windows of these two terminals are displayed with a predetermined size, and the display positions of these windows are synchronously controlled. However, such a structure has following problems. That is, an anchor object called a “marker” is necessary in an HTML (Hyper Text Markup Language) document to synchronously control the display positions of the windows, a specific support server is necessary to support handling of the anchor object, and it is difficult to secure compatibility between the terminal and an application used in the terminal.
As described above, in IP telephone terminals, a technique which can easily and inexpensively display the same net content on the plural terminals under telephone call and perform synchronous control of net content display (scroll) positions and browser window sizes of these terminals as maintaining high compatibility for the terminals and application software of the terminals is not known.
For the meantime, because there is no technique in the IP telephone terminals by which the same net content is displayed on the plural terminals under the telephone call and the displays on the plural terminals are synchronously controlled, the telephone call and the browsing of the net content are all controlled manually in the existing circumstances. For example, when two terminal users who are performing telephone call wish to browse a net content of the same page, following complicated operations are necessary. That is, the terminal users inform of the net content mutually by voice telephone call each other, and then each terminal user handles his own terminal based on the obtained information to browse the target net content. Alternatively, one of the terminal users makes and transmits an electronic mail which includes the URL of the target net content to the other of the terminal users while these users are performing the voice telephone call, and then the terminal user who received the electronic mail browses the target net content by referring to the URL included in the received electronic mail.
Moreover, even when the same net content can be browsed after such a complicated procedure, there are various problems for the browsing operation afterward.
For example, when the two users perform the telephone call as browsing the same net content, the conversation cannot be performed smoothly if both the users cannot surely browse the same content. However, according to the conventional structure, because the browsing is manually controlled by the user, there is a fear that the one user is browsing the content although the other user has already scrolled the browser to see another content or jumped to another linked site.
Moreover, for example, in a sales telephone service that a sales person and a customer perform telephone call as they are browsing and watching the same net content, when plural kinds of sales items (i.e., commodities) and explanations thereof are displayed within the same content page at all once, if one of the content pages is scrolled, there is a fear that agreement of sale is made although the target item watched and recognized by the sales person is different from the target item watched and recognized by the customer. In such a case, serious damage and economic loss may occur according to the content of sales.
Therefore, it is desirable to provide a structure for performing control so that both the two terminal users who are performing the telephone call can surely browse the same Internet resource.
Moreover, even when the net content of the same page can be browsed after the above complicated procedure, because a screen size to be displayed for browsing on each terminal is dependent on the device itself of the terminal in question, following inconveniences occur. For example, there is a fear that the screens are displayed in different layouts on the respective terminals which are under the telephone call. Besides, there is a fear that, although the user on one terminal can see a portion within the page of the screen displayed on the one terminal, the user on the other terminal cannot see the same portion within the page of the screen displayed on the other terminal if this page is not scrolled.
Therefore, in order to perform the control so that both the terminal users who are performing the telephone call can surely browse the same Internet resource, it is necessary to ensure a mechanism which can prevent that a difference in the information content on the Internet resource to be transmitted to the respective terminal users occurs due to a difference in the display functions (i.e., display capability) of the terminals of these users.